Substitute natural gas can be produced by a nickel-catalysed methanation reaction using the effluent from a coal/biomass gasification process. However, compounds of sulfur can severely poison nickel catalysts and are often unavoidable in the effluent (commonly up to 5000 ppm) since sulfur is a component of most coal supplies. When nickel is immobilised on an aluminium oxide substrate for use as a catalyst, it is necessary to remove substantially all of the sulfur contained in the feed gas before allowing it to enter the methanator. In particular, it is necessary to reduce the sulfur content of the feed gas to a level of less than about 0.1 ppm, since sulfur poisons the nickel catalyst if it is present in any higher concentration. The gas cleaning process to remove sulfur down to 0.1 ppm imposes additional capital and processing costs. Therefore, there is a need for a nickel catalyst possessing a higher sulfur tolerance than Ni/Al2O3 so as to minimise the costs of substitute natural gas production.
It is an object of the invention to at least partially satisfy the above need.